The present invention relates to a semiconductor device and a battery monitoring system.
According to a conventional technology, a plurality of battery cells is connected in series to constitute an assembled battery for generating a high voltage. In general, a conventional battery monitoring semiconductor device is provided for measuring and monitoring a battery voltage of the battery cells of the assembled battery.
A conventional battery monitoring system formed of the conventional battery monitoring semiconductor devices, for example, may include a plurality of assembled batteries, and the conventional battery monitoring semiconductor devices are connected in a daisy chain arrangement for monitoring each of the assembled batteries. The conventional battery monitoring system may further include a control unit for controlling each of the conventional battery monitoring semiconductor devices.
In the conventional battery monitoring system, a power source for an external load is provided as a separate device (a separate component) other than the control unit or the conventional battery monitoring semiconductor devices, and may be formed of a power source system separated from the conventional battery monitoring semiconductor devices. Alternatively, in order to reduce a size of the conventional battery monitoring semiconductor devices or the number of wiring portions, there has been proposed a conventional technology, in which a voltage generated in the conventional battery monitoring semiconductor devices is utilized as a power source voltage. According to such a conventional technology, it may be configured such that the power source voltage is supplied from only one of the conventional battery monitoring semiconductor devices that is directly connected to the control unit.
According to the conventional technology described above, when the power consumption of one of the conventional battery monitoring semiconductor devices supplying the power voltage is increased, the power consumption of the assembled batteries may exceed that of the other of the conventional battery monitoring semiconductor devices. Accordingly, a voltage balance among the assembled batteries may become unstable, thereby causing a fluctuation in the voltage of the assembled batteries.
Patent Reference has disclosed a conventional battery monitoring system for reducing the fluctuation in the voltage of the assembled batteries.
Patent Reference: Japanese Patent Publication No. 2014-82152
In the conventional battery monitoring system disclosed in Patent Reference, the conventional battery monitoring semiconductor devices are connected in the daisy chain arrangement, and one of the conventional battery monitoring semiconductor devices is capable of communicating with the control unit (a microcomputer) through an insulation I/F. When the one of the conventional battery monitoring semiconductor devices communicates with the control unit, the power consumption of the one of the conventional battery monitoring semiconductor devices is increased for supplying an electrical current to the insulation I/F. Accordingly, it is possible to reduce a difference in the power consumption of the other of the conventional battery monitoring semiconductor devices, thereby making it possible to reduce the fluctuation in the voltage of the assembled batteries.
In the conventional battery monitoring system disclosed in Patent Reference, when an external load electrical current for supplying the power source to the insulation I/F is fluctuated, however, it is difficult to maintain the power consumption at the constant level. Accordingly, it is difficult to effectively reduce the fluctuation in the voltage of the assembled batteries. Further, the power consumption of the assembled batteries may be increased to an excessive level.
In view of the problems of the conventional battery monitoring system described above, an object of the present invention is to provide a semiconductor device and a battery monitoring system capable of reducing power consumption and a fluctuation in a voltage of assembled batteries.
Further objects and advantages of the invention will be apparent from the following description of the invention.